The packaging density of various electronic systems continues to increase, and the functions are becoming more and more diversified. At present, the performance of the existing single materials cannot meet the demand. In the future, electronic packaging materials will continue to develop in the direction of multiphase compounding.
(1) Research on material system with serialized performance
SIP will involve multiple chips, multiple interconnects, multiple packages, multiple assemblies, and multiple tests in one packaging unit, so its materials must necessarily have multiple properties. For example, the dielectric constant of the material should be adjustable from 9 to 95 serialization; the thermal expansion coefficient serialization can make the substrate well match with a variety of chips and packaging structures, increasing the reliability of the entire module; shrinkage rate serialization adjustable It can meet the co-firing of different ceramic materials and so on. Therefore, the serialized ceramic materials can well realize the diversified requirements of SIP on the performance of materials and meet the packaging requirements in optical, mechanical, and electrical aspects.
Single plastic encapsulation materials, metal encapsulation materials and ceramic encapsulation materials all have one or more shortcomings when applied to SIP, so it is necessary to find a material with good comprehensive performance. Composite materials are composed of one or several materials together, and have various excellent properties of component materials, which is a feasible way to solve the diversified requirements of SIP for materials.
(2) Research on ultra-high thermal conductivity ceramic materials
With the continuous development of electronic chips in the direction of high performance, high speed and high integration, the heat value and relative heat flux of electronic components are getting higher and higher, and the heat dissipation problem has gradually become one of the key technologies to be solved by electronic components. In order to realize the diverse functions of the system, SIP must also be inextricably linked with high thermal conductivity materials.
To solve the heat dissipation problem of electronic components, in addition to more efficient cooling technology, high thermal conductivity materials with thermal conductivity between 300 ～ 400W / m · K and ultra-high thermal conductivity materials with thermal conductivity greater than 400W / m · K And, new packaging materials with thermal expansion coefficients matching semiconductor materials are becoming more and more research hotspots.
Carbonaceous materials have extremely high thermal conductivity and low density, and some materials have high strength. They are an indispensable type of packaging materials in the future and will also play an important role in SIP. In particular, the fourth-generation chip material, graphene, is also a carbonaceous material, and the use of similar materials to encapsulate it will inevitably have unparalleled advantages in thermal expansion matching. Carbonaceous materials mainly include: diamond, carbon fiber, carbon nanotube, etc. However, due to technical limitations, various carbonaceous materials are mainly used as the second additive to improve the thermal conductivity of composite materials. The main research direction in the future is three-dimensional carbonaceous materials, such as diamond sintering technology, carbon fiber three-dimensional preparation technology, C / C composite material preparation technology, etc.
(3) Development of new nano ceramics
The new nano-ceramic powders prepared by the synthesis process of nano-powders such as sol-gel method and co-precipitation method have many properties that traditional ceramic materials do not have. For example, Si-AI-ON material may have the characteristics of high thermal conductivity of AIN material, as well as the high strength of silicon nitride and the good dielectric properties of silicon oxide; AI-BN material may be more traditional than traditional The AIN / BN composite material has more excellent thermal conductivity and the sintering temperature may be lower. Therefore, the development of new nano-ceramics will promote the development of SIP technology.
(4) Development of low-dimensional materials
In order to meet the requirements of high density, high frequency, and high integration, packaging has developed in the three-dimensional direction, and the internal specific structural units have introduced light and thin low-dimensional structures. Thin-film materials have been widely used in the field of high-density packaging. In the future, with the increasing requirements for miniaturization of electronic components, traditional three-dimensional materials or even two-dimensional materials may not meet the requirements, and the packaging material unit is likely to develop into one-dimensional materials (fibers or whiskers). For example, low-K ceramic fiber cloth can be used to replace the ceramic substrate for insulation; the surface or inside of the ceramic fiber cloth can be sub-micron metal fiber for wiring to conduct the circuit; high thermal conductivity carbon fiber is used to replace the heat dissipation substrate for heat dissipation Function; Finally, use a material with a certain strength and good sealing performance to seal the load. In this way, the system function can be ensured, and the flexibility of the fiber material can be used to make the package part close to the chip to reduce the package area, and the finer metal fiber has good conductivity. A certain whisker-like material is implanted into the SIP to play a role as an element; the whisker or fiber composite ceramic substrate is prepared to achieve a good heat dissipation through the one-dimensionally aligned materials, and the base material can use materials with good mechanical properties Play a good supporting role. These all play a revolutionary role in the miniaturization and functional integration of SIP.
Integrated microsystem technology has gradually become the main development direction of miniaturization of electronic devices, and the integration of multiple types of chips inside it has put forward more diverse demands on the external packaging structure. SIP technology can well meet the requirements of integrated microsystem packaging diversity. However, first of all, related research needs to be carried out from the basic substrate materials to realize serialization and diversification of material properties, in order to meet the diversified needs of the system for packaging.